Efeito do treinamento isométrico com handgrip na pressão arterial ambulatorial e modulação autonômica cardíaca de hipertensos: um estudo multicêntrico

Abstract

Evidence has suggested that isometric handgrip training (IHT) is an effective strategy for promoting reductions in resting blood pressure (BP). However, the effects and underlying mechanisms of this modality on ambulatory BP, a superior predictor of cardiovascular risk compared to resting BP, remain uncertain. The aim of this study was to analyze the effects of IHT on ambulatory BP and cardiac autonomic modulation in hypertensive adults. A randomized, controlled clinical trial was conducted in four Brazilian cities, including medicated, sedentary, non-smoking, non-diabetic hypertensive adults with no other cardiovascular diseases, who were randomized into two groups: IHT or Control (CG). The IHT group performed four 2-minute sets at 30% of maximal voluntary contraction, with 1-minute rest intervals between sets and alternating hands, three times per week for 24 weeks. The CG performed the same protocol in a sham manner using a stress ball. Resting BP, ambulatory BP (24-hour, daytime and nighttime), nocturnal dipping, morning surge, and cardiac autonomic modulation were assessed before, and after 12 and 24 weeks of intervention. The study included 139 hypertensive participants (IHT = 70; CG = 69), analyzed by intention to treat. After 12 weeks, resting systolic BP decreased by −7.0 ± 1.2 mmHg compared with pre-intervention in the IHT group and remained reduced after 24 weeks (−7.2 ± 1.6 mmHg). After 24 weeks, the CG also showed a reduction (−7.2 ± 1.6 mmHg). Resting diastolic BP did not decrease in either group (p > 0.05). Ambulatory systolic BP and 24-hour mean BP, as well as daytime diastolic BP, were reduced after 12 and 24 weeks compared with pre-intervention in the IHT group, with no statistically significant changes observed in the CG. Between-group comparisons showed that 24-hour mean BP was lower in the IHT group compared with the CG after 24 weeks. No significant changes were observed in morning surge, nocturnal dipping, or heart rate variability in either group (p > 0.05 for all). In conclusion, IHT elicits a time-dependent response, and in the long term, it does not produce additional reductions in resting systolic BP; however, the initial reductions are maintained. On the other hand, IHT was effective in reducing ambulatory systolic BP, 24-hour mean BP, and daytime diastolic BP in hypertensive adults. Nonetheless, it did not modify nocturnal dipping, morning surge, or cardiac autonomic modulation.